1. Field of the Invention
The present invention relates generally to a folding electronic device such as a folding mobile phone, and more particularly to a waterproof structure for a folding electronic device. It should be noted that the term of “mobile phone” used in this description and claims includes a Personal Handyphone System (PHS) phone.
2. Description of the Related Art
A folding mobile phone has a structure such that a first housing having an input portion and a transmitting portion and a second housing having a display portion and a receiving portion are foldably connected with each other through a hinge mechanism. As to an electrical structure, an electronic component mounted in the first housing and an electronic component mounted in the second housing are connected with each other through a cable or a flexible printed wiring board. The hinge mechanism has not only an original function of foldably connecting the first housing and the second housing, but also a function of maintaining the distance and angle between a receiver and a microphone as required for use as a telephone in consideration of the ergonomically positional relation therebetween.
A mobile phone usable anywhere at any time is essential in the modern society, and it is desired to provide a folding mobile phone having a waterproof structure, which can be used even in the rain, after sea bathing, or in the bathroom of a spa, for example. However, the waterproof structure for the folding mobile phone has not yet been put to practical use because the waterproof structure for the hinge mechanism is difficult to realize. The hinge mechanism is required to have a high degree of waterproofness because of its required opening/closing durability, e.g., a durable lifetime corresponding to at least one hundred thousand of opening/closing operations. Further, it is also necessary to consider deterioration in waterproofness due to the deformation or damage to a case of the mobile phone when a drop impact is applied. Thus, the object can be achieved only for a heavy-duty product such as an outdoor style product.
Japanese Patent Laid-open No. 2002-319771 discloses a folding portable communication terminal capable of effecting a dripproof function for a contact between a flexible printed wiring board and a connector. This folding portable communication terminal has a structure such that an input portion and a display portion are foldably connected with each other through a hinge and that an electronic component mounted in the input portion and an electronic component mounted in the display portion are connected with each other through a flexible printed wiring board. The input portion and the display portion are respectively provided with insertion portions for allowing the insertion of the flexible printed wiring board in the vicinity of the hinge. At least one of these insertion portions is provided with a pair of packings abutting against the front and rear surfaces of the flexible printed wiring board.
In the folding portable communication terminal as described in the above-cited publication, a simple dripproof structure is provided by making the pair of packings abut against the front and rear surfaces of the flexible printed wiring board. However, any completely waterproof structure is not given for the hinge portion for pivotably connecting the input portion and the display portion. For example, in the case that the portable communication terminal is immersed in the water, the entry of water into the device cannot be completely prevented.